1. Field of the Invention
The present invention relates generally to a multicylinder internal combustion engine and, more particularly, to an improvement for the equal distribution of the fuel-air mixture to the cylinders of a multi-cylinder engine.
2. Description of the Prior Art
Various methods for equally distributing the fuel-air mixture between the cylinders of a multi-cylinder engine have been devised and demonstrated, but none of them is satisfactory in practice. In order to improve the equal distribution of the fuel-air mixture in a multi-cylinder engine under full load, a method has been proposed for modifying the configurations of a multi-branched intake manifold, heating the riser of the intake manifold or reducing the diameter of the intake ports, but such method is also unsatisfactory in practice. Another method has been proposed for disposing a device including a rotary blade assembly, a fixed blade assembly and a pipe with wire gauze immediately below a carburetor for improving the atomization of the liquid fuel, but this method cannot ensure the equal and uniform distribution of the fuel-air mixture.
The distribution of the fuel-air mixture between the cylinders under full engine load is dependent upon the direction of the fuel-air mixture flow from the carburetor to the intake manifold, and the direction of the fuel-air mixture flow changes depending upon the engine speed. Especially in the case of a multi-barrel carburetor, the direction of the fuel-air mixture flow is dependent upon the operations of the individual carburetor barrels. Therefore, satisfactory equal and uniform distribution of the fuel-air mixture may be attained at a certain engine speed range, but not over the whole range of the engine speed. At some engine speeds, the fuel-air mixture distribution becomes even worse.
However, when the tendency of the fuel-air mixture to flow in one direction after it has been discharged from the carburetor into the intake manifold is suppressed and then the fuel-air mixture is forced to flow in a predetermined direction, the equal and uniform distribution of the fuel-air mixture may be improved over the whole engine speed range.